Showing papers by "Devendra Jalihal published in 2015"
17 Dec 2015
TL;DR: The original protocol, the detailed findings from the Marathi pilots, and the proposed modifications to the protocol are presented, which consist of a 45-minute long training session, a 20-word first-time usability test, and a longitudinal test consisting of about 30 sessions.
Abstract: We were asked to evaluate input mechanisms for touch-screen devices with the objective of standardising one of them for each of 14 major languages of India. For this purpose, we propose a protocol that consists of a 45-minute long training session, a 20-word first-time usability test, and a longitudinal test consisting of about 30 sessions, each of which required the user to type about 10 phrases 4 to 6 words long (a total of 300 phrases). The evaluation should be done with school children from standards 4th to 7th. The course of the evaluation may last 2-4 weeks for each user. To help follow the protocol over this long period and to collate the data, we offer a tool. Currently, we provide test corpora for Assamese, Bengali, Gujarati, Hindi, Kannada, Marathi, Odia, Tamil, Telugu, and Urdu. We have ensured that each corpus represents a mix of informal communication between people, popular phrases from films, songs, poetry and public discourse, and formal texts from school books and literature. We have tagged each phrase according to typing difficulty, phrase length, and memorability and age appropriateness. We evaluated the protocol through pilot tests with 206 users in Marathi, Gujarati, Hindi, Bengali, Odia, Assamese and Tamil. In this paper, we present the original protocol, the detailed findings from the Marathi pilots, and the proposed modifications to the protocol.
6 citations
01 Sep 2015
TL;DR: In this article, both the traditional and recent techniques for precoding are investigated and schemes proposed for their implementation in the framework of 802.11ac WLAN standard, and the use of these techniques in the implementation of WLAN standards is an open question.
Abstract: Among the linear precoding techniques block diagonalization (BD) based schemes are well-known transmit strategies employed in the downlink of multiuser MIMO (MUMIMO) systems. Employing BD type precoding algorithms at the transmit side suppresses multi-user interference (MUI) by converting a MU-MIMO broadcast channel into multiple single-user MIMO (SU-MIMO) channels and then decomposing the SU-MIMO channels into multiple independent parallel sub-channels. Substantial work has been done in designing linear precoding algorithms. However, the use of these techniques in the implementation of WLAN standards is an open question. In this paper both the traditional as well as the recent techniques for precoding are investigated and schemes proposed for their implementation in the framework of 802.11ac WLAN standard.
3 citations
Posted Content•
15 Jun 2015
TL;DR: The asynchronous communication framework permits a tradeoff between sync frame length, N , and channel, Q, to support asynchronism and allows the synchronization threshold with sync frame energy for the wireless channel to be characterized.
Abstract: In \cite{Chandar2008}, Chandar et al studied a problem of sequential frame
synchronization for a frame transmitted randomly and Uniformly in an interval
of size $A$ slots. For a discrete memory-less channel, they showed that the
frame length $N$ must scale as $e^{\alpha(Q) N} > A$ for the frame detection
error to go to zero (asymptotically with $A$). $\alpha(Q)$ is defined as the
synchronization threshold for the discrete memory-less channel and depends on
the channel transition probabilities $Q$. In our paper, we study the sequential
frame synchronization problem for a fading channel and additive noise and seek
to characterize the effect of fading. For a discrete ON-OFF fading channel
(with ON probability $p$) and additive noise (with channel transition
probabilities $Q_n$), we characterise the synchronisation threshold of the
composite channel $\alpha(Q)$ and show that $\alpha(Q) \leq \alpha(Q_n) \times
p$. We then characterize the synchronization threshold for Rayleigh fading and
AWGN channel as a function of the fading and noise parameters. The asynchronous
communication framework permits a trade-off between sync frame length, $N$, and
channel, $Q$, to support asynchronism. This allows us to characterize the
synchronization threshold with sync frame energy for the wireless channel.
Posted Content•
TL;DR: The asynchronous framework permits a trade-off between sync frame length, N, and channel, Q, to support asynchronism, and this allows us to characterize the synchronization threshold with sync frame energy instead ofsync frame length.
Abstract: In \cite{Chandar2008}, Chandar et al studied a problem of sequential frame synchronization for a frame transmitted randomly and uniformly among $A$ slots. For a discrete memory-less channel (DMC), they showed that the frame length $N$ must scale as $e^{\alpha(Q)N}>A$ for the frame detection error to go to zero asymptotically with $A$. $\alpha(Q)$ is the synchronization threshold and $Q$ is channel transition probability. We study the sequential frame synchronisation problem for a fading channel and additive noise and seek to characterise the effect of fading. For a discrete ON-OFF fading channel (with ON probability $p$) and additive noise (with channel transition probabilities $Q_n$), we characterise the synchronisation threshold of the composite channel $\alpha(Q)$ and show that $\alpha(Q)\leq p\,\alpha(Q_n)$. We then characterize the synchronization threshold for Rayleigh fading and AWGN channel as a function of channel parameters. The asynchronous framework permits a trade-off between sync frame length, $N$, and channel, $Q$, to support asynchronism. This allows us to characterize the synchronization threshold with sync frame energy instead of sync frame length.